Surface-mount electronic component packages (hereinafter referred to as “packages”) are applicable to electronics devices and the like, specifically to surface-mount piezoelectric resonator devices (hereinafter referred to as “piezoelectric resonator devices”) such as crystal resonators, crystal filters, and crystal oscillators.
A piezoelectric resonator device includes a crystal resonator plate with metal film electrodes on both principal surfaces of the crystal resonator plate. The crystal resonator plate is disposed in a package. The package hermetically seals the metal film electrodes to protect the metal film electrodes from ambient air. Piezoelectric resonator devices of this kind generally have packages made of ceramic material in view of demands associated with surface mounting of parts (see, for example, Patent Citation PLT 1).
PLT 1 discloses a surface-mount resonator as a piezoelectric resonator device. The surface-mount resonator includes a base (referred to as “a mounting board” in PLT 1) made of ceramic material and a lid (referred to as “a cover” in PLT 1). The casing of the surface-mount resonator is composed of a rectangular parallelepiped shaped package. In the internal space of the package, a piezoelectric resonator piece (referred to as “a quartz crystal piece” in PLT 1) is held and bonded on the base. The package with the piezoelectric resonator piece held and bonded therein is bonded on a circuit board made of glass epoxy material with a solder, thus electrically connecting the circuit board to an external connection terminal formed on the base.